1. Field of the Invention
The present invention relates to a receiver apparatus, a junction cable, and a power supply apparatus, which are applicable to, for example, a mobile telephone that can receive digital television broadcast. The invention makes it possible to configure an earphone antenna with a simple and small configuration while ensuring sufficient mechanical strength, by using a multicore coaxial cable for the cable for transmission of signals and electric power and cutting only the covered wire of the multicore coaxial cable at a mid portion thereof so that it can partially function as an antenna.
2. Description of Related Art
Mobile telephones that can receive television broadcast or the like in the past have received broadcast waves by built-in antennas or external antennas. The built-in antenna has an advantage that it does not spoil the styling of the mobile telephone. However, the built-in antenna has some drawbacks. For example, it is poorer in sensitivity than the external antenna, and it tends to be affected easily by internal noise.
On the other hand, examples of the external antenna include a telescopic antenna and an earphone antenna. The telescopic antenna has an advantage of better sensitivity than the built-in antenna. However, the telescopic antenna has some drawbacks. For example, it spoils the styling of the mobile telephone, and the antenna protrudes from the mobile telephone.
In particular, when the reception frequency is lower, the length of the antenna needs to be longer. In the case of the telescopic antenna, the antenna protrudes from the mobile telephone considerably, degrading the styling of the mobile telephone significantly. Specifically, for a UHF band with a frequency of 470 to 770 [MHz], the length of a monopole type telescopic antenna needs to be about 150 [mm]. On the other hand, for a VHF band with a frequency of 100 to 200 [MHz], the length of a monopole type telescopic antenna needs to be about 800 to 400 [mm]. Thus, the telescopic antenna protrudes from the mobile telephone considerably for the VHF band, degrading the styling thereof significantly.
In contrast, an earphone antenna uses a cable for an earphone as the antenna. The earphone antenna can prevent sensitivity deterioration and the adverse influence of internal noise without degrading the styling of the mobile telephone.
Regarding the earphone antenna, JP-A-2006-25392 discloses a configuration in which a high-frequency cut-off circuit is provided at a mid portion of a cable and only the cable on the device side from the high-frequency cut-off circuit is allowed to function as an antenna. The configuration of JP-A-2006-25392 can prevent performance deterioration resulting from the approaching and contacting of the earphone cable to a human body.